Medium for use in making camera copy and method of preparing the same



June 17, 1952 M. D. MOINTOSH 2,601,161

MEDIUM FOR USE IN MAKING CAMERA COPY AND METHOD OF PREPARING THE SAMEFiled Aug. 19, 1948 INVENTOR. MAURlCE D. M INTOSH ATTORNEY Patented June17, 1952 MEDIUM FOR USE IN MAKING CAMERA COPY AND METHOD OF PREPARINGTHE SAME Maurice'D. McIntosh, ClevelandHeights, Ohio, assignor to LouisS. Sanders, Shaker Heights,

Ohio

Application August 19, 1948, Serial No. 45,058

4 Claims. (Cl. 41-41) This invention relates, as indicated, to a mediumfor use in making camera copy, and to a method of preparing the same.

In my Patent No. 2,355,884, I have described a drawing paper in whichone pattern in the form of small dots, is superimposed over another, inthe form of larger dots, both patterns being formed in such a mannerthat registry between two different printing plates, as described in myReissue Patent No. 20,503, is not necessary. The method involvesseparate and distinct steps forapplying the chemicals constituting thetwo dot patterns, and also involves a step of removing a varnish imprintwith a solvent, as well as certain other procedural difficulties.

I have discovered that I can eliminate one or more of the stepsheretofore thought necessary in making a drawing medium of the characterdescribed, while retaining the advantages of such a medium, particularlythe advantage of perfect registry or proper relative location betweenthe difierent patterns, by preparing the medium in accordance with themethod to be now described.

The invention can probably best be understood by reference to theaccompanying drawing, wherein Fig. 1 is a perspective view of a fragmentof a base sheet which is used for preparing the medium of the presentinvention;

Fig. 2 is a fragmentary elevational view of the base sheet of Fig. 1,but showing the application of the dots in accordance with the firststep of my method;

Fig. 3 is a fragmentary cross-sectional view, taken on the line 3-3 ofFig. 2;

Fig. 4 is a view similar to Fig. 2, but showing the manner in which thesecond series of dots is formed;

Fig. 5 is a fragmentary cross-sectional view. taken on the line 5-5 ofFig. 4;

Fig. 6 illustrates the production of one tone value by development ofthe smaller series of dots, and

Fig. 7 illustrates the production of a greater tone value by developmentof both series of dots.

Referring more particularly to the drawing, and especially to Fig. 1, irepresents a white paper base sheet, which is provided on one or bothsides thereof with laminations or coatings 2 of a colorlesswater-impermeable material, such, for example, as cellulose acetate,cellulose nitrate, ethyl cellulose, vinyl acetate, vinyl chloride, andthe like.

One of the laminations or coatings 2 is coated or covered with a verythin lamination or sheet 2 1 3 of a non-moisture-proof cellophane or agelatin coating, which cellophane or gelatin should be insoluble butpermeable to water solutions.

Instead of utilizing a cellophane covered base sheet, as described, Imay, if I so desire, start with a sheet of unmounted cellophane of thecharacter described.

Then, by means of a printing plate, as used in ordinary letter pressprinting, I apply to the cellophane or gelatin surface, a pattern ofdots 4, which, as shown in Figs. 2 and 3, are circular, but may besquare or any other desired shape, the dots being spaced from each otherin a manner similar to the spacing of dots in an ordinary Ben Daypattern. Such dots, in actual practice, are extremely small and spacedvery closely together, but the size and spacing are greatly enlarged inthe present drawing, for purposes of clarity.

The ink or solution, of which the dots 4 are composed, contains thefollowing ingredients:

- Grams LePages Liquid Glue -4 48 Glycerin 24 Mercurous chloride -l 350Water f :50 Diethylene glycol Cobaltous chloride (Co C12.6H2O) Theingredients forming this ink are milled on a conventional stone mill or3 roll mill.

After a short interval of time, the merourous chloride which cannotpermeate the cellophane or gelatin, remains in its in situ or appliedposition, on the surface of the cellophane or gelatin. and does notbecome enlarged. It forms the small circular dot 5, shown in Figs. 4 and5.

During this time interval, the cobaltous chloride, which is permeable inthe cellophane or gelatin, migrates or diffuses into the cellophane orgelatin, and spreads uniformly in all directions therein, forming thelarger circular dots 6, shown in Figs. 4 and 5, on which e dots 5 aresuperimposed.

After the dots 6 have grown to a desired size, and suflicient contrastbetween the respective dots 5 and 6 has been obtained, the dots arefixed by means of a fixing agent consisting of the following ingredientParts Sodium tungstate (Na2WO42I-I2O') 1U Formalin (40% formaldehyde) 5Water This fixing agent, through double decomposition, precipitates thesoluble cobaltous chloride as 3 insoluble cobaltous tungstate, whichprevents further migration or enlargement of the dots 6. At the sametime, the formaldehyde in the Formalin insolubilizes the glue vehicle ofthe ink, thereby binding or fixing the mercurous chloride dots 5.

The length of the time interval between the printing and fixing stepswill determine the relative size of the dots and accordingly therelative tone value of the patterns. The superimposed dots mustnecessarily be smaller than the underlying dots in order to secure auseful difference in the final tone values.

The medium, as thus prepared, exists as a cellophane or gelatin film,containing a white (actinic color) insoluble chemical dot patternconsisting of a series of uniformly spaced dots 6 of cobaltoustungstate, and a series of mercurous chloride dots superimposed upon thecobaltous tungstate dots and of a smaller uniform size, thesuperimposition of one series of dots upon another resulting in an exactregistration or proper relative location between the dots.

The medium thus prepared is the medium of the present invention for usein making camera copy.

After a suitable drawing, as for example, an ink line drawing, has beenmade upon the medium, one or both of the patterns may be developed indesired areas as a shading of or accompaniment to such line drawing.

In order to develop the dots 5, a chemical developer consisting of a 5%aqueous solution of thiourea is applied to the sheet, as by means of abrush, thereby changing the mercurous chloride dots to a black or brownnon-actinic color and producing a Ben Day tone of one value, as shown inFig. 6. In order to develop a tone of a deeper or darker value, achemical developer consisting of a 4% aqueous solution of sodiumsulphide is applied to the sheet, as by means of a brush, therebychanging both the cobaltous tungstate and mercurous chloride dots to ablack or brown color, and producing a Ben Day tone of greater value, asshown in Fig. 7.

It is thus seen that I have provided a method of preparing camera copyof the type described in my Patent No. 2,355,884, but in which I haveeliminated the step of forming one series of dots, and have alsoeliminated other steps entailing labor and expense.

It is to be understood that various changes may be made in the detailsof the method and medium without departing from the spirit and scope ofthe invention.

Having thus described my invention, I claim:

1. In a method of preparing a medium for use in making camera copy, thesteps which consist in applying to a non-moisture-proof surface, asolution containing at least two ingredients, one of which remainssuperficially on said surface as a chemically-developable patterncomprising uniformly spaced dots, and the other of which impregnatessaid surface and spreads uniformly in all directions to form a secondpattern comprising spaced dots larger than said first-named dots and inregistration with said first-named dots, the ingredient forming thefirst-named dots being mercurous chloride, and the ingredient formingthe larger dots being cobaltous chloride.

2. A method, as defined in claim 1, in which the cobaltous chloride dotsare subjected to treatment which converts them to insoluble cobaltoustungstate, and the mercurous chloride dots are insolubilized bytreatment with a chemical containing formaldehyde.

3. A method, as defined in claim 2, in which the insolubilized mercurouschloride, is developable by means of thiourea, and the cobaltoustungstate dots and mercurous chloride dots are simultaneouslydevelopable by means of sodium sulphide.

4. A medium for use in preparing camera copy, said medium consisting ofa surface having chemically-developable patterns, one of said patternsconsisting of uniformly spaced dots of one' substance disposed belowsaid surface, and the other of said patterns consisting of uniformlyspaced dots of another substance smaller than said first-named dots andsuperimposed upon the latter, and disposed above said surface, the dotsbelow the surface containing cobaltous tungstate and the dots above saidsurface containing mercurous chloride.

MAURICE D. McINTOSH.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date Re. 20,503 McIntosh Sept. 14,1937 2,355,884 McIntosh Aug. 15, 1944

1. IN A METHOD OF PREPARING A MEDIUM FOR USE IN MAKING CAMERA COPY, THESTEPS WHICH CONSISTS IN APPLYING TO A NON-MOISTURE-PROOF SURFACE, ASOLUTION CONTAINING AT LEAST TWO INGREDIENTS, ONE OF WHICH REMAINSSUPERFICIALLY ON SAID SURFACE AS A CHEMICALLY-DEVELOPABLE PATTERNCOMPRISING UNIFORMLY SPACED DOTS, AND THE OTHER OF WHICH IMPREGNATESSAID SURFACE AND SPREADS UNIFORMLY IN ALL DIRECTIONS TO FORM A SECONDPATTERN COMPRISING SPACED DOTS LARGER THAN SAID FIRST-NAMED DOTS AND INREGISTRATION WITH SAID FIRST-NAMED DOTS, THE INGREDIENT FORMING THEFIRST-NAMED DOTS BEING MERCUROUS CHLORIDE, AND THE INGREDIENTS FORMINGTHE LARGER DOTS BEING COBALTOUS CHLORIDE.